The first embodiment of this invention relates to a cut resistant jacket for ropes, webbing, straps, inflatables and the like, more particularly a cut resistant article comprising a cut resistant jacket surrounding a less cut resistant member where the jacket comprises a fabric of a yarn and the yarn consists essentially of a high strength, longitudinal strand having a tensile strength of at least 1 GPa and the strand is wrapped with a fiber.
The second embodiment of this invention relates to cut resistant yarns and their use in protective garments. There are many applications for such protective garments. Meat processing employees exposed to sharp knives require such garments. Metal and glass handlers who must be protected from sharp edges during the handling of materials may use such protective garments. Medical personnel who are exposed to scalpels and other sharp instruments may obtain protection through the use of such garments.
It is known to make cut resistant fabric for gloves used for safety in the meat cutting industry. For example see U.S. Pat. No. 4,470,251, U.S. Pat. No. 4,384,449 and U.S. Pat. No. 4,004,295 all hereby incorporated by reference. It is also known to make a composite line containing two different filamentary materials in the form of a core and a jacket of different tensile strengths and elongations as in U.S. Pat. No. 4,321,854 hereby incorporated by reference. It is also known to make composite strand, cables, yarns, ropes, textiles, filaments and the like in other prior U.S. patents not cited herein.
In the prior art, U.S. Pat. No. 3,883,898 suggests that an aramid fiber, such as "Kevlar", be used in cut resistant gloves that are worn by meat processors. U.S. Pat. No. 3,953,893 teaches using an aramid fiber in cut resistant aprons.
U.S. Pat. No. 4,004,295 suggests the use of a glove composed of yarn of metal wire and a nonmettalic fiber such as an aramid fiber as protection from knife cuts, especially in meat processing plants. U.S. Pat. No. 4,384,449 and 4,470,251 also suggest the use of metal wire in combination with aramid fibers.
U.S. Pat. No. 4,651,514 suggest the use of a yarn composed of a monofilament nylon core that is wrapped with at least one strand of aramid fiber and a strand of nylon fiber. The stated advantage of this yarn over that suggested in, for example, U.S. Pat. No. 4,004,295 is that this yarn is electrically nonconductive.
By ultrahigh molecular weight is meant 300,000 to 7,000,000. Normal molecular weight is then below
By fiber herein is meant any thread, filament or the like, alone or in groups of multifilaments, continuous running lengths or short lengths such as staple.
By yarn herein is meant any continuous running length of fibers, which may be wrapped with similar or dissimilar fiber, suitable for further processing into fabric by braiding, weaving, fusion bonding, tufting, knitting or the like, having a denier less than 10,000.
By strand herein is meant either a running length of multifilament end or a monofilament end of continuous fiber or spun staple fibers, preferably untwisted, having a denier less than 2,000, or, regarding the first embodiment only, metal of diameter less than 0.01 inches.
For many applications, cut resistant garments made using the prior art have undesirable disadvantages or limitations. Garments made using only high strength polyethylene or other fibers offer improved levels of cut protection. However, very sharp edges, such as newly sharpened knives, can cut even very cut resistant fibers with only moderate cutting forces. The addition of metal wire to a yarn containing one of the above high strength fibers can improve yarn cut resistance. Even very sharp edges can have difficulty cutting through a yarn made of aramid and metal fiber. However, such yarns are much less flexible due to the stiffness of the metal. If a garment is too stiff the wearer may become fatigued by using it, or in an extreme case may remove the garment and lose the intended protection. Repeated use and flexing of the garment may cause the relatively stiff metal wire to break. In this case it is likely that the broken wire ends will protrude from the yarn. These sharp wires protruding from the garment may scratch the wearer or any objects being handled.
The use of metal wire in a cut resistant yarn makes the yarn electrically conductive. This means that a garment made with such a yarn cannot be used in contact with high-voltage electrical equipment. The use of a nylon monofilament, instead of metal wire, in a cut resistant yarn removes the problem of electrical conductivity. However, the use of nylon monofilament results in a less cut resistant yarn. The nylon is much more easily cut by very sharp edges than is metal wire. Therefore, the yarn as a whole is more easily cut.
The present invention overcomes many of the limitations of cut resistant yarns made using the prior art. The present invention can have a cut resistance equal to or better than that obtained by using yarn containing metal wire, however, it does not have the stiffness or electrical conductivity associated with a yarn containing metal wire.